How about common sense?
By their analysis--100,000 casualties, of which 2/3 are in Fallujah--Fallujah has suffered about 70,000 dead civilians in a city of about 300,000. This is a stunning quantity, over twice the number Iraqi casualties, military and civilian, in the entire Gulf War.
It always amazes me when otherwise intelligent people just don't go, "hey, wait a minute."